Abstract: A violent tornado occurred in Funing County, Yancheng City in June 23, 2016, causing heavy casualties and enormous property loss. Based on meteorological data, such as weather maps and doppler weather radar maps, the mechanism of the tornado was analyzed. Then the range of wind speed exceeding 42 m/s was estimated based on the conclusion inferred by other author that “when the wind speed reaches about 42 m/s in the gale, the percentage of broken trees in the woods rises sharply to 50%”, according to the investigation data of the broken trees in the five areas where the disaster was relatively serious. The results show that atmospheric unstable stratification, cold, warm and humid air intersection, wind vertical shear can induce tornadoes; the length of range of the tornado wind speed exceeding 42 m/s is at least 20 km, and the maximum width is at least 952 m.

Key words: tornado, broken trees, wind speed, range of influence